mₑ · electron mass

전자 질량

Takeaway

The relative standard uncertainty fell by a factor of about 19,285 from the 1969 to the 2022 edition (5.9×10⁻⁶ → 3.1×10⁻¹⁰): the error bars narrowed that much.
Of 9 earlier editions with a measured value, 8 have the 2022 value outside ±1σ (the error bar) and 6 outside ±2σ (the bar doubled); the normal expectation is about 1 in 3 and 1 in 22.
The largest move between editions came in 2018→2022, at 3.1 times the combined standard uncertainty of the two editions (|z| = 3.1).

Unit: kg
Note: = 2R∞h/(cα²). A combination of core constants, so left out of the statistics.
M1: Half-life (years): 3.96 (3.04–5.69)

Value ±1σ by edition2022

Relative deviation from the 2022 value (symmetric-log axis). Open circles: the error bar does not reach the 2022 value. Squares: exact.

Editionyear of the recommended values (data cut-off)	As printedexactly as in the source table; digits in parentheses are the standard uncertainty in the last digits	Standard uncertaintyhalf-width of the error bar (±1σ)	Relative standard uncertaintystandard uncertainty ÷ \|value\|: bar width relative to the value	z vs previous editionmove from the previous edition ÷ combined standard uncertainty of the two	z vs 2022(2022 value − this value) ÷ this edition's standard uncertainty	Source locationpage and table of the paper, or file and line of NIST's table
1969	9.109558(54) e-31	5.4×10⁻³⁶	5.9×10⁻⁶		−3.2275	477 table XXXII
1973	9.109534(47) e-31	4.7×10⁻³⁶	5.2×10⁻⁶	−0.3352	−3.1976	718 table 33.1
1986	9.1093897(54) e-31	5.4×10⁻³⁷	5.9×10⁻⁷	−3.0501	−1.1085	codata86 p.9 table 2
1998	9.109 381 88(72) e-31	7.2×10⁻³⁸	7.9×10⁻⁸	−1.4354	2.5471	1998 ASCII:92
2002	9.109 3826(16) e-31	1.6×10⁻³⁷	1.8×10⁻⁷	0.4104	0.6962	2002 ASCII:93
2006	9.109 382 15(45) e-31	4.5×10⁻³⁸	4.9×10⁻⁸	−0.2707	3.4753	2006 ASCII:94
2010	9.109 382 91 e-31	4.0×10⁻³⁸	4.4×10⁻⁸	1.2623	2.0097	2010 ASCII:99
2014	9.109 383 56 e-31	1.1×10⁻³⁸	1.2×10⁻⁸	1.5668	1.3991	2014 ASCII:99
2018	9.109 383 7015 e-31	2.8×10⁻⁴⁰	3.1×10⁻¹⁰	1.2859	4.4286	2018 ASCII:106
2022	9.109 383 7139 e-31	2.8×10⁻⁴⁰	3.1×10⁻¹⁰	3.1315		2022 ASCII:107